Reduced-Power External Main Oscillator | Jameco Electronics 2000

16.10 Reduced-Power External Main Oscillator

The circuit in Figure 16-13can be used to generate the main clock using less power than with the built-in oscillator buffer. The power consumption is less because of the current- limiting resistors that cannot be used with the built-in buffer. The 2.2 kΩ series resistor must be reduced as the clock frequency increases, as must be the current-limiting resistors.

	To Rabbit 3000
	XTALA1	2.2 kW	33 pF
		2.2 kW	33 pF
+3.3 V	SN74HCT1G04DBVR
		1 MW	3.68 MHz
		1 MW	(CL = 20 pF)
			(CL = 20 pF)
Optional current-reducing			33 pF
Optional current-reducing
	resistors

Figure 16-13. Reduced-Power External Main Oscillator

Table 16-8lists results for the reduced-power external oscillator with no current-limiting resistors.

Table 16-8. Current Draw Using Reduced-Power External Oscillator

(0 Ω current-limiting resistors)

Voltage	Current (incl built-in buffer)
(V)	(mA)

3.3	0.635

2.5	0.380

1.8	0.252

Design Recommendations

•Add current-limiting resistors to reduce current without inhibiting oscillator start-up

•Increase the 1 MΩ resistor to improve gain

•Minimize loop area to reduce EMI

236	Rabbit 3000 Microprocessor

Image 245

Jameco Electronics 2000, 3000 manual Reduced-Power External Main Oscillator, Voltage Current incl built-in buffer

Contents

Page Rabbit 3000 Microprocessor Rabbit Semiconductor Trademarks Table of Contents Rabbit Internal I/O Registers Parallel Ports 129 Rabbit 3000 Clocks 209 Appendix B. Rabbit 3000 Revisions 273 Rabbit 3000 Microprocessor Introduction Features and Specifications Rabbit User’s Manual 1shows a block diagram of the Rabbit CPU Summary of Rabbit 3000 Advantages Differences Rabbit 3000 vs. Rabbit Feature Rabbit Serial ports with support for SDLC/HDLC IrDA Rabbit 3000 Design Features Rabbit 8-bit Processor vs. Other Processors Serial Ports Overview of On-Chip Peripherals and Features1 5 V Tolerant Inputs 4 32.768 kHz Oscillator Input System Clock Cascaded Output Registers for Parallel Ports D and E Parallel I/O Rabbit Slave Port Auxiliary I/O Bus Timers PWM Input Capture Channels Pulse Width Modulation Outputs Quadrature Encoder Inputs Design Standards Separate Core and I/O Power PinsSpread Spectrum Clock Programming Port Dynamic C Support for the Rabbit Standard Bios Rabbit 3000 Microprocessor Processor Registers Details on Rabbit Microprocessor Features Rabbit 3000 Microprocessor Addressing Memory Components Memory Mapping Example of Memory Mapping Operation 4shows a memory interface unit Extended Code Space Use of XPC Segment Separate I and D Space Extending Data Memory Xpc window stack Using the Stack Segment for Data Storage Data RAM Root Code Practical Memory Considerations User’s Manual Instruction Set Outline Load or Store Data from or to a Constant Address Load Immediate Data to a Register Other 8-bit loads and stores are the following Load or Store Data Using an Index Register Register Exchanges Register-to-Register Move 7 16-bit Arithmetic and Logical Ops Push and Pop Instructions Bool SBC instruction can also be used to perform a sign extension Input/Output Instructions Zero HL in 4 Clocks How to Do It in Assembly Language-Tips and TricksExchanges Not Directly Implemented Manipulation of Boolean Variables Comparisons of Integers HLB Atomic Moves from Memory to I/O Space Interrupt Priority Interrupt Structure Processor Priority Effect on Interrupts Effect of Processor Priorities on Interrupts Privileged Instructions, Critical Sections and Semaphores Multiple External Interrupting Devices Critical Sections Semaphores Using Bit B,HL Computed Long Calls and Jumps Precisely Timed Output Pulses Rabbit Capabilities Pulse Width Modulation to Reduce Relay Power Open-Drain Outputs Used for Key Scan Using Open-Drain Outputs for Key Scan Cold Boot Slave Port Slave Rabbit As a Protocol Uart PIN Assignments and Functions Pinout Lqfp Package Same pin dimensions apply along the x axis and the y axis Mechanical Dimensions and Land Pattern PC Board Land Pattern for Rabbit 3000 128-pin Lqfp Ball Grid Array Package C D E F G H J K L M Design Considerations All dimensions in mm Ball and Land Size DimensionsKey Feature Recommendation Nominal Ball Tolerance Ball Pitch Nominal Land BGA Package Outline Rabbit Pin Descriptions Rabbit Pin DescriptionsPin Pin Group Pin Name Direction Function Numbers Lqfp Tfbga Vddcore Bus Timing Read and Write Bus Timing Pins With Alternate Functions Description of Pins with Alternate Functions PF7 PWM3 AQD2A Parallel Port x Alternate Functions Control Bits Parallel Port x Alternate Functions 3 Volt DC Characteristics DC CharacteristicsSymbol Parameter Maximum Rating Symbol Parameter Test Conditions Min Typ Max Units I/O Buffer Sourcing and Sinking Limit Rabbit 3000 Microprocessor Rabbit Internal I/O Registers On-Chip Peripheral ISR Starting Address Rabbit 3000 Peripherals and Interrupt Service Vectors Rabbit Internal I/O Registers Default Values for all the Peripheral Control RegistersRegister Name Mnemonic Address Reset Grev PEB7R PWM0R Tbcsr Sdar Global RAM Configuration Register Global ROM Configuration RegisterMiscellaneous Functions Processor Identification Global CPU Register Rabbit Oscillators and ClocksGlobal Revision Register Gcpu Rabbit Clock Select Field of Gcsr Global Control/Status RegisterGlobal Control/Status Register Gcsr Clock Doubler Recommended Delays Set In Gcdr for Clock DoublerGlobal Clock Double Register Gcdr Effect of Clock Doubler User’s Manual Reduction in Peak Spectral Strength from Spectrum Spreader Clock Spectrum Spreader Chip Select Options for Low Power Address = 0x0D Global Power Save Control Register Short Chip Select Memory Read Global Output Control Register Gocr = 0x0E Output Pins CLK, STATUS, /WDTOUT, /BUFEN Time/Date Clock Real-Time Clock 11. Real-Time Clock Control Register Rtccr adr = 10. Real-Time Clock RTCxR Data Registers 12. Watchdog Timer Control Register Wdtcr adr = Watchdog Timer 13. Watchdog Timer Test Register Wdttr adr = System Reset Pin Name Direction Reset Low Post-Reset† Recognized by CPU 14. Rabbit 3000 Reset Sequence and State of I/O Pins Rabbit Interrupt Structure 15. Interrupts-Priority and Action to Clear Requests External Interrupt Line Logic External Interrupts Reg Name Reg Address Bits 7,6 Bits 5,4 Bits 3,2 Bits 1,0 Interrupt Vectors INT0 EIR,0x00/INT1 EIR,0x0816. Control Registers for External Interrupts Bootstrap Operation 102 Rabbit 3000 Microprocessor Pulse Width LSBs 1st 2nd 3rd 4th Pulse Width Modulator 18. PWM MSB x Register 17. PWM LSB x Register Input Capture 106 Rabbit 3000 Microprocessor Iccsr 19. Input Capture Control/Status RegisterInput Capture Control/Status Register 21. Input Capture Trigger x Register 20. Input Capture Control RegisterIccr ICT1R 24. Input Capture MSB x Register 22. Input Capture Source x Register23. Input Capture LSB x Register Quadrature Decoder Rejected Qdcsr 25. Quadrature Decoder Control/Status RegisterQuad Decode Control/Status Register 27. Quadrature Decoder Count Register 26. Quadrature Decoder Control RegisterQdcr QDC1R 114 Rabbit 3000 Microprocessor Interface for Static Memory Chips Memory Interface and Mapping RAM RabbitData Lines Static Address Lines Memory Flash Processor Memory Mapping Unit Interface Memory Chips Memory Mapping OverviewMemory-Mapping Unit Segment Registers 64KSegment Size Register Segment Register Function Memory Interface Unit Memory Bank Control Register x MBxCR = 0x014 + Memory Bank Control Registers MMU Instruction/Data Register Mmidr = Optional A16, A19 Inversions by Segment /CS1 EnableMMU Instruction/Data Register Mmidr MMU Expanded Code Register Memory Timing Control Register MTCR, adr =Mecr Memory Timing Control Register Breakpoint/Debug Control Register BDCR, adr = 0x01C Allocation of Extended Code and DataBreakpoint/Debug Control Register Bdcr Instruction and Data Space Support RAM Use of Physical Memory Separate I & D Space Model How the Compiler Compiles to Memory 128 Rabbit 3000 Microprocessor Parallel Ports Parallel Port a Data Register Bit Functions Parallel Port aParallel Port a Registers Parallel Port B Register Bit Functions Parallel Port BParallel Port B Registers Parallel Port C Register Bit Functions Parallel Port CParallel Port C Registers Parallel Port D Registers Parallel Port D PD7 Bits 7 Bits 5 Bits 3 Bits 1 Parallel Port D Register functionsParallel Port D Control Register adr = 136 Rabbit 3000 Microprocessor PE0 Parallel Port E 10. Parallel Port E Registers 12. Parallel Port E Control Register adr = 11. Parallel Port E Register functions 14. Parallel Port F Register Functions Parallel Port F13. Parallel Port F Registers 15. Parallel Port F Control Register adr = 0x03C Using Parallel Port a and Parallel Port F Summary Parallel Port a Parallel Port F 17. Parallel Port G Data Register Functions Parallel Port G16. Parallel Port G Registers Parallel Port G Control Register adr= 0x04C Write data Write strobe T1 Tw T2 10. I/O Bank Control RegistersRead data Read strobe Chip select strobe External I/O Timing with 1 wait state I/O Bank x Control Register Control Register Port E Address Pin A1513 Range External I/O Register Address Range and Pin Mapping 148 Rabbit 3000 Microprocessor Timers Reload Register Operation Timer a Timer a I/O Registers Timer a I/O Registers Tacsr Timer a CapabilitiesTimer a Control and Status Register User’s Manual 153 Timer a Prescale Register Timer a Control RegisterTacr Tapr Practical Use of Timer a Register Name Mnemonic Reset Address Timer BTimer B Registers Timer B Control Register Timer B Control and Status RegisterTbcsr Tbcr 10. Timer B Count LSB x Registers Timer B Count MSB x Registers11. Timer B Count MSB Register 12. Timer B Count LSB Register Using Timer B 160 Rabbit 3000 Microprocessor Rabbit Serial Ports Serial Port SignalsSerial Port Signal Name Function Clka User’s Manual 163 Serial Port Register Layout Signals Shown at Microprocessor Tx Pin User’s Manual 165 Serial Port a Registers Serial Port RegistersSerial Port B Registers Serial Port C Registers Serial Port F Registers Serial Port D RegistersSerial Port E Registers Address Register All Ports Data Register All Ports 10. Long Stop Register All Ports 11. Status Register Asynchronous Mode Only All Ports 12. Status Register Clocked Serial Ports A-D only Bits Value Description Clocked serial mode only Bits Value Description Hdlc mode only 13. Status Register Hdlc Mode Ports E and F only Sbcr 14. Serial Port Control Register Ports a and BSacr Sccr 15. Serial Port Control Register Ports C and DAddress = 0xE4 Sdcr Secr 16. Serial Port Control Register Ports E and FAddress = 0xCC Sfcr 17. Extended Register Asynchronous Mode All Ports 18. Extended Register Clocked Serial Mode Ports A-D only 19. Extended Register Hdlc Mode Ports E and F only Transmitter IRQ Serial Port Interrupt Transmit Serial Data Timing Serial Port Synchronization Receive Serial Data Timing Clocked Serial Ports Clock Polarities Supported in Clocked Serial Mode User’s Manual 183 184 Rabbit 3000 Microprocessor Clocked Serial Timing with External Clock Clocked Serial TimingClocked Serial Timing With Internal Clock Valid Synchronous Communications on Ports E and F Last Byte Bit Pattern Valid Data Hits User’s Manual 189 190 Rabbit 3000 Microprocessor User’s Manual 191 Push AF IOI LD A,SCSR Serial Port Software Suggestions Transmitting Dummy Characters Controlling an RS-485 Driver and Receiver Transmitting and Detecting a Break Using a Serial Port to Generate a Periodic Interrupt Parity, Extra Stop Bits with 8-Data-Bit Characters Parity, Extra Stop Bits with 7-Data-Bit CharactersStop bit Start bit Data bits 9th bit low Stop bit Data Framing/Modbus Supporting 9th Bit Communication ProtocolsRabbit-Only Master/Slave Protocol User’s Manual 197 198 Rabbit 3000 Microprocessor SRD SCS Rabbit Slave Port Slave Port Read Cycle Following table explains the parameters used in Figure Symbol Parameter Minimum Maximum Slaveattn PB7 Typical Connection Slave Rabbit to Master Rabbit Slave Port Registers Hardware Design of Slave Port InterconnectionSlave Port Registers Register Mnemonic Internal Address External Address Bit Bits 6,5 Bit 3,2 Bits 1,0 Write Only Read Only Slave Port Control Register Spcr adr = Slave Port Status Register Spsr adr = Applications and Communications Protocols for SlavesSlave Applications Master-Slave Messaging Protocol 208 Rabbit 3000 Microprocessor Rabbit 3000 Main Oscillator Circuit Rabbit 3000 Clocks Low-Power Design EMI Control Using the Clock Spectrum Spreader Power Supply Connections and Board Layout Spread Spectrum Mode Select Spread Spectrum Enable/Disable RegisterGCM0R GCM1R 214 Rabbit 3000 Microprocessor Memory Access Time AC Timing SpecificationsAccess Enable Access MHz Memory Requirements at 3.3 V, -40C to +85C, Adr Bus 60 pF Normal Strong 30 pF 60 pF 90 pF No dbl/dbl Data and Clock Delays VDD ±10%, Temp, -40C-+85C maximumVDD CSx Time Delay Output Capacitance 30 pF 60 pF 90 pF Memory Read Time DelaysMemory Write Time Delays CLK A190 CSx WEx D70 Example Clock Doubler Max-Min Clock Low Times 222 Rabbit 3000 Microprocessor Bufen 16.2 I/O Access Time I/O Write Time Delays I/O Read Time Delays Further Discussion of Bus and Clock Timing Clock Doubler and Memory Timing Maximum Clock Speeds at 3.3 V Preliminary Maximum Clock SpeedsConditions Commercial Ratings Industrial Ratings Period Frequency External Oscillator Buffer User’s Manual 229 Power and Current Consumption Rabbit 3000 System Current vs. Frequency at 3.3 11. Sleepy Mode Current Consumption Current Consumption Mechanisms Sleepy Mode Current Consumption Memory Current Consumption Current is negligible for V 1.14 Battery-Backed Clock Current Consumption Voltage Current incl built-in buffer Reduced-Power External Main Oscillator Bios Services Rabbit Bios and Virtual DriverBios Watchdog Timer Support Bios AssumptionsVirtual Driver Periodic Interrupt User’s Manual 239 240 Rabbit 3000 Microprocessor Other Rabbit Software Power Management Support Reading and Writing I/O Registers Using Assembly LanguageUsing Library Functions Updating Shadow Registers Shadow RegistersInterrupt While Updating Registers Atomic Instruction Non-atomic Instructions Timer and Clock UsageWrite-only Registers Without Shadow Registers Format of the structure used is the following 246 Rabbit 3000 Microprocessor Summary Rabbit Instructions Flag Description Spreadsheet Conventions Rabbit Z180 Meaning Symbols Load & Store to Immediate Address Load Immediate Data19.3 8-bit Indexed Load and Store 19.4 16-bit Indexed Loads and Stores Register to Register Moves 19.5 16-bit Load and Store 20-bit Address 19.9 16-bit Arithmetic and Logical Ops Exchange InstructionsStack Manipulation Instructions ADD A,HL 19.10 8-bit Arithmetic and Logical Ops 19.12 8-bit Increment and Decrement 19.11 8-bit Bit Set, Reset and Test 19.14 8-bit Shifts and Rotates 19.13 8-bit Fast a Register Operations Block Move Instructions Instruction Prefixes Miscellaneous Instructions Control Instructions Jumps and Calls Following instructions are privileged Privileged Instructions Differences Rabbit VS. Z80/Z180 Instructions Z80/Z180 Instructions Dropped Rabbit Instructions to Use Flag Register Key IOI and IOE I Column Symbol Key Rabbit Z180 Meaning Z V C EX AF,AF LD A,BC LDP HL,IX RRA 268 Rabbit 3000 Microprocessor Programming Port PIN Assignments Appendix A. the Rabbit Programming Port Alternate Programming Port Use of the Programming Port as a Diagnostic/Setup Port Suggested Rabbit Crystal Frequencies Non-Stock Crystals Appendix B. Rabbit 3000 Revisions 274 Rabbit 3000 Microprocessor User’s Manual 275 Table B-1. Summary of Rabbit 3000 Improvements and Fixes Discussion of Fixes and ImprovementsRabbit Description 3000 3000A IL1T/IZ1T IL2T/IZ2T Rabbit Internal I/O Registers Table B-2. Reset State of New Rabbit 3000A I/O Registers Iuer Rabbit Register Name Mnemonic 3000 3000A Address Reset On-Chip Peripheral Address Range ISR Starting Address Peripheral and ISR Address User’s Manual 281 Table B-5. Rabbit 3000 Revision Identification Information Revision-Level ID RegisterProcessor Revision Package Gcpu Grev System/User Mode Table B-6. Write Protect Control Register Memory ProtectionWrite Protect Control Register Wpcr Wplr Table B-7. Write Protect Low RegisterWrite Protect Low Register Table B-9. Write Protect Segment x Register Table B-8. Write Protect High RegisterWphr Wpsar Write Protect Segment x Low Register Table B-10. Write Protect Segment x Low RegisterWpsalr Wpsblr Write Protect Segment x High Register Table B-11. Write Protect Segment x High RegisterWpsahr Wpsbhr Figure B-2. Simple Stack Protection Layout Stack Protection Table B-14. Stack High Limit Register Table B-12. Stack Limit Control RegisterTable B-13. Stack Low Limit Register Table B-15. RAM Segment Register RAM Segment RelocationRAM Segment Register Ramsr Table B-16. Watchdog Timer Control Register-Updated Secondary Watchdog TimerTable B-17. Secondary Watchdog Timer Register Wdtcr Table B-18. New Rabbit 3000 Opcodes New OpcodesInstruction Bytes Clks Operation New UMA/UMS Opcodes New Block Copy Opcodes Table B-19. Rabbit 3000 Revision Block Copy Opcode EffectsSource Destination IOI/IOE Table B-20. MMU Instruction/Data Register Expanded I/O Memory Addressing Table B-21 Bank x Control Register External I/O Improvements Address = 0x000D Table B-22. Global Power Save Control RegisterShort Chip Select Timing for Writes Table B-24. Clock Select Field of Gcsr Clock Select and Power Save ModesTable B-23. Global Control/Status Register Figure B-3. Short Chip Select Timing CLK/8, Read Operation Short Chip Select Timing Figure B-4. Short Chip Select Timing CLK/6, Read Operation Figure B-6. Short Chip Select Timing CLK/2, Read Operation Figure B-7. Short Chip Select Timing 2 kHz, Read Operation Figure B-9. Short Chip Select Timing 8 kHz, Read Operation Figure B-11. Short Chip Select Timing 32 kHz, Read Operation Figure B-12. Short Chip Select Timing CLK/8, Write Operation Figure B-13. Short Chip Select Timing CLK/6, Write Operation Figure B-15. Short Chip Select Timing CLK/2, Write Operation Figure B-16. Short Chip Select Timing 2 kHz, Write Operation Figure B-18. Short Chip Select Timing 8 kHz, Write Operation 310 Rabbit 3000 Microprocessor Figure B-21. PWM Interrupt and Output Timing Pulse Width Modulator Improvements Table B-26. PWM LSB 1 Register Table B-25. PWM LSB 0 RegisterPWM LSB 0 Register PWM LSB 1 Register Address = 0x008E Table B-27. PWM LSB 2 and 3 RegistersAddress = 0x008C Table B-28. Quadrature Decoder Control Register Quadrature Decoder ImprovementsTable B-29. Quadrature Decoder Count High Register QDC1HR User’s Manual 315 Serial Ports E/F Pins with Alternate Functions Table C-1. Differences Between System and User Modes Appendix C. SYSTEM/USER ModeSystem Mode User Mode Instruction Bytes Clk Operation Priv System/User Mode OpcodesTable C-2. New System/User Mode Opcodes Table C-3. System/User Mode I/O Registers System/User Mode Registers Register Name Mnemonic Address Table C-4. I/O Addresses Inaccessible in User Mode Interrupts Figure C-1. Interrupt Handing in System/User Mode Peripheral Interrupt Prioritization Table C-5. Interrupts-Priority and Action to Clear Requests Memory Protection Only Using the System/User Mode Figure C-3. System/User Mode Setup for Mixed Operation Mixed System/User Mode Operation Complete Operating System Figure C-4. System/User Mode Setup for Operating System Table D-1 Rabbit 3000A Internal I/O Registers Appendix D. Rabbit 3000A Internal I/O Registers Table D-1. Rabbit 3000A Internal I/O Registers 0x03C0 00000000 Serial Port E User Enable Register 0x006A Xxxxxxxx Port D Bit 3 Register 0x0082 00000000 Bank 3 Control Register 0x0098 Xx000000 Interrupt 1 Control Register 0x00D1 Xxxxxxxx Serial Port B Long Stop Register 334 Rabbit 3000 Microprocessor User’s Manual 335 Page Numerics Index Memory A16, A19 inversions /CS1 PWL2R, PWL3R 200